Overview
General
The GPC-XP is a software driven, multi-function controller which can
be congured to a variety of applications from simple on/off time clock
control to more complex sequences involving multiple input and outputs
control based on basic logic functions.
The purpose of this guide is to illustrate the GPC-XP capability for Water
Source Heat Pump Central Plant control applications.
GPC-XP Used As A WSHP Loop Controller
The GPC-XP Controller can be congured to control the central water
loop for individual water source heat pumps installed in a typical water
source heat pump system. See Figure 2 for a general layout of a typical
Water Source Heat Pump system.
The GPC-XP can operate stand-alone or be used with the Auto-Zone
2 (AZ 2) Control System to utilize the transfer of commonly shared
information such as outside air temperature and proof of water ow
over a communication network.
The main purpose of the GPC-XP controller, when used as a Water
Source Heat Pump Loop Controller, is to provide water ow in the sys-
tem when needed. It also maintains the proper loop water temperature
required at any given time by monitoring either the Loop Return Water
Temperature or the Loop Supply Water Temperature. The settings should
typically be congured to supply between approximately 60° F to 90° F
water temperatures to the installed water source heat pumps. Generally
any loop water temperature below 60° F would require heat addition
(hot water boiler) and any loop water temperature above 90° F would
require heat rejection (closed circuit cooling tower).
When a higher water temperature is required, (water is below the de-
sign loop water temperature) the cooling bypass valve is energized and
bypasses the cooling tower and the heat addition (hot water boiler) is
enabled by the controller to heat the water to the required temperature.
The heat addition setpoints are fully adjustable and can be set according
to your systems requirements.
When a lower water temperature is required in the loop, (water is
above the design loop water temperature) the cooling bypass valve is
de-energized and the cooling tower is enabled by the controller to bring
on a cooling tower fan and tower spray pump to cool the water to the
required temperature. The heat rejection setpoints are fully adjustable
and can be set according to your systems requirements.
The AZ 2 Unit Controller can be congured to control individual water
source heat pumps. The AZ 2 Controller will work in conjunction with
the GPC-XP Loop Controller to send and receive data critical to an ef-
cient WSHP system.
For additional information about the Auto-Zone 2 control system, please
visit our web site at www.az2controls.com for complete information
and resources.
GPC-XP Controller
Features
Controller
• Stand-alone or network operation.
• Onboard time clock
• Built in USB port for direct connection to computer
• Status indicators for:
• Power
• Communications
• Binary inputs
• Relay outputs
• Congurable controller provides exibility for variations in
the application.
Software
• Purpose built Prism front end graphical software eliminates
programing. Simple conguration through point & click
selection and drop down menus
• Prism software is free to download from AZ 2 web site
Conguration and Setpoints for:
• Outside air low limit
• Pump control:
• On/Off based on time schedule or demand call
• Variable ow pump control based on differential
pressure
• Proof of ow
• Minimum runtime timers
• Automatic lead/lag changeover to equalize pump
usage
• Automatic pump failure changeover
• Runtime counters
• Boiler control:
• Adjustable setpoints
• Boiler enable
• Automatic loop temperature control
• Bypass valve control
• Proof of run
• Boiler fail alarm
• Emergency shutdown
• Cooling Tower:
• Adjustable setpoints
• Tower Fan – on/off and VFD
• Spray pump
• Spray pump proof of ow
• Sump heater control
• Monitor sump water temp
• Built in USB port for direct connection to computer
Introduction
3
WSHP Loop Controller GPC-XP Guide
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